Cloning/Transcript
Transcript Text reads: The Mysteries of Life with Tim and Moby Tim' is seated at his computer. The BrainPOP homepage is on his screen, and he sees a live image of himself looking through the same computer screen. Tim waves his hand and his live image mirrors his movements. His voice echoes when he speaks.'' '''MULTIPLE TIMS: Weird. Moby hands' him a sheet of paper. Tim reads from the typed letter.'' '''TIM: Dear Tim and Moby, What can you tell me about cloning? From, Frieda. Funny you should ask. Clones are organisms, or parts of organisms, that share the same exact genetic information. Believe it or not, people have been creating them for thousands of years. Ancient farmers cloned crops by cutting off a piece of a plant and replanting it somewhere else. An animation shows an ancient farmer carefully cutting a branch from a plant with a small knife. TIM: That technique is called, er, cutting. And in the early 1900s, scientists started experimenting with splitting animal embryos in the lab, to create twins. This can also happen naturally, before birth—the result it identical twins with DNA from both parents. Creating a cloned animal from a single adult parent is more difficult. An animation shows a single embryo dividing into two identical ones. Inside each embryo is the outline of two figures, each with a DNA double helix inside them. An image shows the outline of a single sheep with a double helix inside of it. MOBY: Beep? TIM: In 1996, scientists used a single adult sheep cells to produce a cloned sheep named Dolly. An animation shows a sheep standing in a pasture. It is joined by another, identical, sheep. TIM: Their process revolved around DNA, the molecule that carries genetic information. DNA was removed from one cell nucleus, copied, and injected into another. The technique used to create Dolly required the help of three different sheep: One provided the DNA, which was injected into the egg cell from the second one, and the third one carried the pregnancy. An image shows Dolly, along with three other slightly different-looking sheep. A DNA double helix appears above the first sheep and then moves into an egg cell that appears above the second sheep. The egg cell with the DNA then moves to the stomach of the third sheep. TIM: But this isn't the only way to create clones. Scientists are always experimenting with new options, because clones could be really useful. The best livestock could be cloned on farms. An image shows a line of identical cattle, standing in a field. TIM: And we may soon be able to clone new organs and body parts for people with diseases and injuries. An image shows a doctor performing surgery on a patient. TIM: One day, cloning could even bring extinct animals back to life using DNA in remnants of their fur or bones. An image shows a wooly mammoth, standing in a snowy field. TIM: But as exciting as it is, there are still problems with cloning. MOBY: Beep? TIM: Well, for one thing, that sheep, Dolly? She died at a pretty young age and she develop arthritis early on in her life. Most scientists agree that, even when she was a baby, it was hard to say whether that was because of the cloning process. When scientists later used the same cells Dolly came from to make more clones, they turned out very healthy. An animation shows two scientists watching a sheep standing on a hillside. TIM: Identical DNA can pose other risks. Let's say a virus comes along that's deadly for some wheat plants. In a normal crop of wheat, that's no big deal. Some of the wheat will die, and some won't since their different DNA gives them different traits.An animation shows a field of wheat. A single wheat plant withers and dies. TIM: But if all the wheat in a crop has the same DNA—and therefore, the same traits—the farmer better hope that that clone is resistant to the virus. If not… An animation shows a field of identical wheat plants. They all wither and die. TIM: Finally, there are ethical questions about cloning. Is it right to clone animals when so many of them develop diseases and age rapidly? Is it ever right to clone human embryos? Well, philosophers and scientists and politicians are still debating these issues. Cloning is a pretty big power for humans to have, and it raises a lot of tough questions. MOBY: Beep. Tim looks at his computer screen and sees a live image of him and Moby on the BrainPOP homepage. Tim looks to his side, but Moby isn't there. TIM: Hey, how'd you do that? Category:BrainPOP Transcripts Category:BrainPOP Science Transcripts Category:BrainPOP Health Transcripts